Triple action heavy duty press



Nov. 10', 1942. J. A MULLER I ,3 1,

mums Ac'ubu .muwr DUTY mass I Filed Aug. 26, '1940 2 Sheets-Sheet 1 Jam MJ'UHANA. MULLER. WTW

Nov. 10, 1942.

J A. MULLER TRIPLEACTION HEAVY DUTY PRESS Filed Aug. 26, 1940 2 Sheets-Sheet 2 Jrwm NJ'OHANA. MULLER,

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Patented Nov. 10, 1942 ACTION HEAVY DUTY PRESS Johan A. Muller, Mount Gilead, Ohio, asslgnor to The Hydraulic Development Corp. Ina, Wilmington, DeL, a corporation of Delaware AppiicationAugust 26, 1940, Serial No. 354,258

'8 Claims. (Cl. 113-45) operation of the second die is electrically ini- This invention relates to presses and in particular to multiple action presses.

Multiple action presses as heretofore known compriseda plurality of metal shaping punches which are to be moved in opposite directions to perform the work piece shaping operation. However, theheretofore known presses of this type were rather complicated in construction and ex pensive in operation.

It is, therefore, an object of the invention to provide a multiple action press, in which the operation of the work piece shaping punches is materially simplified, so as to reduce the cost of construction and operation.

Another object of the invention consists in the provision of a hydraulic multiple action press in which, for shaping the work piece in a plurality of steps, only one power unit is required acting sequentially first through a first ram and then through a. second ram.

' A further object of the invention consists in the provision of amultiple action press adapted to carry out two shaping steps during one cycle, in which a first and a second ram are movable in opposite directions with respect to each other and are hydraulically actuated by the same power unit in such a manner that the second ram remains inoperative during the first shaping step effected'by the first ram, and in which the second ram becomes operative in response to a predetermined pressure acting upon the first ram, while the latter remains stationary during the second shaping step.

It is still another object of the invention to provide a hydraulic multiple action press, in which one shaping ram is associated with the press head, while-another shaping ram is associated with the press bed and adapted to operate through said bed after the first shaping opera-' tion. has been carried out by the'ram associated with the press bed.

It is another object of the invention to provide a multiple action press in which the press head is associated with a first ram adapted to support an upper die-whereas a lower die cooperating with the upper die is arranged on the press bed and in which a second die remains below the surface of the lower die while the pressure action, due to the movement of the upper die, is being completed, whereuponthe second die auto matically becomes operative.

A still further object of the invention consists in the provision of a multiple action presses set forth in the preceding paragraph, in which the tiated.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic illustration of the hydraulic system in a press according to the invntion.

Figures 2, 3 and 4 illustrate subsequent positions during the shaping operation,

Figure 5 illustrates, similar to Figures 2 to 4, the shaping operation of a slightly modified press according to the invention.

General arrangement The present invention comprises a press having a pressing platen associated with an upper die and a hydraulically operable ram carrying a lower die which, during the first pressing step, is held below the upper surface of the press bed. After the first pressing step has been completed, the lower die is hydraulically operated so as to protrude beyond the upper surface of the press bed, thereby engaging and shaping the work piece in a second pressing step. According to a more specific embodiment of the invention,- the first pressing step is a drawing operation, whereas the second step is a stretching operation.

Structural arrangement Referring to the drawings in detail, the press illustrated in Figure 1 comprises a press bed I and a press head 2 connected with each other by strain rods (not shown in the drawings). Supported by the press head 2 are a fluid tank 3, two main variable delivery pumps 4 and 5 and an auxiliary delivery pump 6. The press head has furthermore associated therewith a pressing platen .,l operable by a, main cylinder-pistonassmbly generally designated 8, and auxiliary cylinder-piston-assemblies 9 and I0. v'I'he press head l 'also supports clamping cylinder-pistonassemblies l I and I2 cooperating with the clamping platen l3. Supported by the press bed I is a press bed cylinder it having reciprocably mounted therein a double-acting piston IS with a; punch 16 which in its retracted position, is below the upper surface I! of the lower die I but is adapted, during the second pressing step, to pass through the bore 18 in the press bed and beyond the surface I! of the press bed I.

As will be seen from Figure 1, the press comprises a' plurality of clamping cylinders I9 associated with hollow clamping pistons 20 which are connected with the pressing platen l in any convenient manner so that movement of the.

clamping pistons also moves the clamping platen I3 and vice versa. Communicating with the bore 2| of each clamping piston is a cylinder 22 provided in the pressing platen I and having reciprocably mounted therein a clamping plunger 22a connected with the clamping platen I3. The clamping platen I3 is movable relative to the pressing platen l and is supported thereby by means of a plurality'oi' rods-23, (only one shown), which pass through lugs 24 and 25' connected with the clamping platen I3 and the pressing platen 1 respectively, and carry at their ends nuts or collars 28 and 21. The pressing platen I is furthermore connected with two auxiliary plungers 28 ant-1'23 carrying double-acting pistons 30 and 3i. Arranged between the double-acting pistons 30 and 3i is a single-acting main plunger 32 reciprocable in the main cylinder 33. The main cylinder 33 forms a unit with the auxiliary cylinders 34 and 33 in which the auxiliary pistons 33 and 3i are reciprocably mounted. The hydraulic system illustrated in Figure 1 comprises surge valves 33 and 37 arranged in the auxiliary cylinders 34 and and the surge valve 38 associated with the main cylinder 33. The hydraulic system furthermore comprises cylinder relief and pump by-pass valves 39 and 40. The surge valves 36, 31 and 38 and the valves 39 and 40 do not forma part of the present invention and for a more detailed description thereof reference may be had to U. S. Patent No. 2,193,248 to Ernst, issued March 12, 1940, and the Ernst patent application Serial No. 286,063, filed July 24, 1939. The purpose of the surgevalves 35, 3'! and 38 is to prefill the adjacent cylinder portions of the cylinders 33, 34 and 35- at the beginning of the working stroke of the main pressing plunger 32 and, in cooperationwith the valves 39 and. 40, to relieve the pressure in the upper portion of the cylinders 33, 34 and 35 for facilitating initiation of the retraction stroke of the platen I. The valve 39 is connected with the main cylinder 33 by means of conduits 4|, 42 and 43, while the valve 40 is likewise connected with the main cylinder 33 by means of the conduits 43 and 43. Each of the conduits 42 and 43 has respectively associated therewith a safety valve 45 and 48. The surge valve 38 communicates by means of a conduit 41, conduits 43 and 49 with a conduit 50 which leads through conduits 35 and 33 to one side of the variable delivery pumps 4 and 5 and also communicates with the upper portion of the press bed cylinder I4. A conduit 5hr communicates with a ,two-way or pilot valve 5I which is closed by pressure fluid from the 'servomotor control of pump 5, and is opened by pull-back pressure from conduit 50a. Also communicating with the conduit 48 are conduits 52 and 53 respectively leading to the valves 39 and 40 and being provided with safety valves 54 and Branching off from the conduit 49 and communicating with the conduits 48 and 50 are conduits 56 and 51 respectively provided with check valves 53 and 59 which are adapted to open the conduits I03 and I01.

connected with the servomotor of the pumps 4 7 and 5 is adapted respectively to be'actuated by a solenoid 33, 5311 so as to shift the pumps 4 and 5 to full stroke forward delivery position. The linkage 62, 82a is furthermore operable by a push rod 54 having an adjustable collar mounted thereon which is engaged by the pressing platen I at the end of the retraction stroke in such a manner as to cause the push rod 64 to actuate the linkage 32, 62a so as to shift the 'pumps 4 and 5 to neutral or no-delivery position.

The line 60 connected with the line SI of the two-way valve 5! comprises check valves 61 and 88 opening in opposite directions and respectively communicating with the outermost left and right clamping cylinder bores I3. Branching ofi from the line 60 are lines 69, I0, II and I2, each of which comprises a check valve I3 adapted to communicate through conduits I4, I5, I6 and IT with the adjacent clamping cylinder bores I9. Branching off from the conduitfifl and the conduits 33, 15, i3 and El are conduits I8, it and 83, each comprising a check valve 0i and leadmg respectively to relief valves 82, 83, 84, associated with gauges 85, 8S and 37. The conduits 33, 30 and 33 branching off from the conduits I8, Ti and 60 lead respectively to relief valves BI, 32 and 93 associated with gauges 84, 95 and 96. The relief valves 82, 83 and 84, SI, 32 and 93 areindependently adjustable so as to open at a predetermined pressure, through lines 91 and 98 to the fluid tank 3. Inthis way' different clamping pressures may be obtained with the diiferent clamping cylinders I9.

' The conduit 49 branching of! fromthe conduit 50 leads to the lowermost portion of the auxiliary cylinder and has a branch conduit 99 leading to the surge valve 36 in the auxiliary cylinder-piston-assembly 9. Similarly, the conduit 48 branching oif from the conduit 49 leads to the lowermost portion of the auxiliary cylinder bore 35 and has a branch conduit I00 leading to the surge valve 31 of the auxiliary cylinderpiston-assembly I0. Leading from the upper portion of the auxiliary cylinder bore 34 is a conduit IOI comprising a check valve I02 and adapted to communicate through conduit I03 having a check valve I04 therein with the upper portion of the auxiliary cylinder bore 35. Branchin off from one branch of the conduit IOI is a conduit I05 leading to a two-way valve I03 which is adapted to communicate through conduit iIlI with another branch of the conduit IN. The two-way valve I06 is controllable by a control rod I3'I having adjustably connected therewith a collar- I38 with tapered surfaces adapted to cooperate with a spring urged pin I38 mounted in the platen arm I40. When the platen arm I40 during its downward movement engages the collar I38, it will move the valve I03 downwardly thereby establishing communication between the conduit I01 and the conduit I05 connectedwith Further downward movement of the platen arm I40 will merely cause the pin I39 to slip over the tapered surfaces of the collar I38 while the control. rod I31 remains inits lowermost position. Accordingly, when the platen arm' I40 moves upwardly its pin I33 will again lift the control rod I31 so as to break the connection between the conduits I01 and'I05, and while the platen arm I40 continues its upward movement will cause the pin I33 to slip over the collar I38. The conduit I M is furthermore adapted tobe connected with the tank3 by means of a conduit 108, a tonnage control valve I00 and the conduit H0. The tonnage the pistons II! and I23 control valve 133 is so arranged that a predate minedpressure in the conduit I33 causes thesaid tonnage control valve to close an electric circuit. The tonnage control valve I33 does not form part of the present invention "and for a more detailed description thereof reference may be had to the Ernst patent application Serial No. 214,772, flied June 20, 1938.

Also branching oil from the conduit III is a conduit III leading to the one-way variable delivery pump 3 which comprises a conduit II2 communicating with a servomotor associated with the pump 3 so that a predetermined pressure in the conduit III will cause the pump 3 to shift to neutral position. The auction side of the pump 3 is connected by means of the conduits H3 and H4 withthe fluid tank 3. The pump 3 delivers continuously into the main pressure cylinder 33 regardless of what part of press cycle is being made. The pressure control set associated with the pump 6 is so adjusted as to maintain whatever pressure is desired for clamping the work piece during the upward pressing action of v the lower punch. The said pressure control reduces the ump stroke so that only enough fluid is delivered into the main cylinder to maintain the necessary pressure, that is, to take care of any leakage that may develop.

The conduit IIII leads to a port II! of a control valve, generally designated Ill. The control valve II8 comprises a casing III with a longitudinal bore III in which are reciprocably mounted two pistons III; I23, interconnected by a valve rod I2 I. The valve rod I2I passes through so that the upper portion of the valve rod is guided in the upper portion of the valve casing III, whereas the lower portion of the valve rod forms an armature I22 adapted to cooperate with the solenoid I23 so that energization of the solenoid I23 shifts the pistons Ill and I23 to their lowermost position. when the solenoid I23 is not energized. the valve rod I II is shiftedto its uppermost position by means of a'spring I24. Provided in the cylinder bore III is a recess I25 communicating through port I23 with a conduit I21 leading to one side of the reversible. variable delivery pump and communicating through conduit I23 witha; corresponding side of the reversible variable delivery pump 4. The bore H3 in the valve casing III furthermore comprises a recess I23 communicating through. port I33 with a conduit I3I leading to the lowermost portion of the pres bed cylinder I4. The valve casing III furthermore com-' prises a passageway I33 communicating with the conduit Ill and adapted when the valve pistons H3 and I23 are in their uppermost position to communicate with the port I33. Connected with the conduit IN is a conduit I32 leading to a second tonnage control valve I33 whichin its turn is adapted to communicate through con- Operation Assuming that the pressing platen I is provided withpunches I and I42 as indicated in Figures 2, 3 and 4, and that a work piece I43 supported by the lower die I44 is to be shaped by means of the punches I4I,' I42, the punch l3 and the press cylinder I4, the shaping operation will be eifected in two steps indicated diagrammatically in lf'igures 3and 4.

Providing that all parts of the-press occupy the position shown in Figure 1, which position corresponds to the end of the retraction stroke, the pressing operation is carried out as follows:

The pumps 4 and i and the pump 8 are started in any convenient manner. whereupon the solenoids 33 and "dare energized so as to cause.

the linkage 32, 62a to shift the pumps 4 and 3 to full stroke forward pomtion. The pistons Ill and I23 are in their uppermost position due to the action or the spring I24 so that the port I33 does not communicate with the port I23, while the port I23 communicateswith the port IIS. While the pressing platen I together with the auxiliary pistons 30 and M will now slidethroughthe conduits Ill, IOI, I43 and 43 into the upper portion of the main cylinder 33. Downward movement of the platen I also causes downward movement of the hollow clamping pistons 23, and the clamping cylinder bores I3, will be supplied with fluid flowing from the tank 3 through the check valve II and the conduits l3 and I4 to I1 inclusive. The clamping platen I3 supported by the pressing platen I will of dult I" with a conduit I" leading to the fluid tank 3. The tonnage control valve I33 may be of similar construction as the tonnage control valve I33. However, the tonnage control'valve I33, in contrast to the tonnage control valve Ill, issoarrangedastobreakacircuitresponsive to a predetermined pressure prevailing in the conduit I3I. In order to prevent undue pressure in the conduit I3I and the lower portion of the press bed cylinder I4 if for some reason the tonnage control valve I33 should not operate properly, a safety valve I33 is arranged between the course likewise move downwardly together with the platen I. As soon as the clamping platen I3 engages the work piece I43, the clamping platen I3 comes to a standstill, so that further downward movement of the pressing platen 1 causes a relative movement of the plungers 22s with respect to the cylinders 22. This relative movement. results in a building up of pressure in'the cylinders 22 which pressure is conveyed into the cylinder bores II where it acts .upon the hollow pistons 23, thereby supporting the relative movement of the platen I and cylinders 22 with regard to the piungers 22a and increasing the clamping pressure exerted upon the clamping platen l3. If any excessive pressure should occur in the cylinders-22 and I3. this excessive pressure will be conveyed through the conduits l3, l3 and 33 and the conduits 33, ll and-8| to the relief valves 32, I3 and and the valves GI, 32 and 33, will then open to exhaust.

when the clamping platen I3 is thus firmly pressed against the work piece I43, the punches HI and I42 begin to act upon the work piece I43. Pressurenow builds up in the upper 'portion of the main cylinder 33 and the auxiliary conduit III. and the conduit I35. The. safety cylinders 34 and 33 with the result that the surge valves, 33 and 31 close. At this time the platen arm I43 has caused the controlrod I37 to shift the valve I33 downwardly so as tocomprising the solenoids 63,,63a and I23; The

establish communication between, the conduits I01 and I05. Pressure will therefore also be supplied by the pumps 4 and 5 and the pump 6 through the conduit IN, the conduit I], the two-way valve I06 into the conduit I from 5 where it will flow through the conduits IIJI and I03 respectively into the upper portion of the auxiliary cylinders 34' and 35. The fluid expelled by the auxiliary pistons 30 and 3! is conveyed through the conduits 49 and 38 and the conduits 50, 65, 66, to the suction side of the pumps 4 and 5. Since the fluid conveyed by the pistons 30 and 3I to the suction side of the pumps 4 and 5 is-less than that required by the pressure side of said pumps, additional fluid is taken in from the tank 3 through the check valves 53 and 58 associated with the conduit 39. The pressing platen 'I now performs the first working step as indicated in Figure 3, from which it will be noted that the work piece I43 has been shaped in accordance with the shaping of the punches HI and I42 and the corresponding recesses I46 and I4I in the lower die I44. It will be noted that while the conduit 50 communicating with the upper portion of the press bed cylin- 5 der I4 is connected with the suction side of the pumps .4 and 5, the conduit I3I communicating with the lower portion of the press bed cylinder I4 does not communicate with the pressure line I21. Due to the position of the valve piston I20, the piston I5 remains in its lowermost position in which the punch I6 is below the upper surface H of the lower die 4,.

At the end of the first working step the solenoid I23 is energized in any convenient manner, 3 preferably my conveying the pressure in conduit IOI through the conduit I08 to the tonnage con-' trol valve I09 which, when the pressure in conduit IOI reaches a predetermined value, will be operated so as to close the circuit comprising the solenoid I23. The piston I20 now establishes communication between the ports I26 and I30, while the piston I I3 closes up the port I I5. 'Consequently fluid pressure is now delivered by the pumps 4 and 5 through the conduit I28, conduit I21, port I26, port I30 and conduit I3I into the lower portion of the press bed cylinder I4 so thatthe piston I5 with the punch I6 will gradually move upwardly untilthe piston I5 reaches its uppermost position, thereby shaping the work 5 piece I43 as indicated in Figure 4 of the drawings. During this second shaping step no relative movement between the pressing platen I and the clamping platen I3 takes place, while the clampto neutral position. 1 The fluid expelled by the upward movement of the piston I5 flows through.

the conduits 50, .65, 66, to the suction side of the pumps 4 and5. When at the end of the second shaping step a predetermined pressure is built up in the conduit I3I, this pressure acts through the conduit I32 upon the tonnage control valve I33, thereby actuating the latter so that it breaks the circuit pumps 4 and 5 will therefore, due to the servomotor springs previously referred to, be shifted to full stroke retraction position so that pressure fluid will now flow from the pumps 4 and 5 I through conduits 65 and 66 and the conduits 60,

accuses 49 and 43 into the lower portion of the auxiliary cylinders 34 and 35.

If for any reason the tonnage control valve I33 should get stuck or undue pressure should develop in. the conduit I3I, the excess pressure would be released through the emergency valve I36 and the conduit I35 into the tank 3.

As soon as the pumps 4 and 5 have been shifted to full stroke retraction position, the main cylinder relief and pump by-pass valves 39 and 40 re-= lease the pressure in the upper portions of the cylinders 33, 34 and 35,-thereby facilitating the initiation ofthe retraction stroke. The delivery of pressure fluid by the pumps 4 and 5 to the retraction side of the auxiliary pistons 30 and M causes an upward movement of the press platen I. Simultaneously fluid passes through the conduit 50 into the upper portion of the press bed cylinder I4 thereby moving the punch I6 downwardly and withdrawing the said punch from the work piece. Since, due to the de-energization of the solenoid I23, the spring I24 shifts the valve pistons H9 and I20 again upwardly, the fluid expelled by the downward movement of the piston I5 is passed through the conduit I3 I, the port I30, valve bore II8, passageway I53 and conduit I I0 in part to the pump 6 and in part to the fluid tank 3. The fluid expelled by the pistons 30, 3| and 32 is passed in part through the now open surge valves 36, 31 and 38' into the conduits 49 and. 48 from which it flows to the retraction side of the pistons 30 and 3i and in part through the now open check valves I02 and I04 and through the conduit 43 into the conduit IDI from where it flows through the port II5, valve bore II8,

'port i26 into the conduits I21, I28, leading to clamping platen I3 still rests upon the work piece.

I43. As a result of this relative movement of the pressing platen I and the clamping platen v I3, the space of the cylinders 22 above the upper surface of the plungers 22a gradually increases, while the space of the cylinders I9 above the upper surfaces of the hollow clamping pistons 20 decreases. Consequently, the pressure tending to develop in the cylinders I9 is conveyed through the hollow clamping pistons 20 into the cylinders 22 where it makes up to a certain extent the decrease in pressure occurring in the cylinders 22. In this way the space between the pressing platen I and the clamping platen I3 gradually increases until the lugs 25 connected with the clamping platen I3 engage the nuts 26. From this point on the clamping platen I3 will be lifted in unison with the pressingplaten I. The gradual spacing operation between the clamping platen I3 and the pressing platen I gradually strips the shaped work piece from the punches HI and I42. The stripping oi' the work piece from the punchI 6 is effected by the retraction of e. latter in the manner previously described. I

The fluid pressure time line 60a, generated by pumps 4 and 5 and acting through conduits 50, 49 and 48, acts upon the pilot valve 5I so as to effect communication between the conduit 60 and the tank 3, through the exhaust opening (not shown) in valve 5|. in the cylinders I9, due to sticking of valve 6|,

Any excessive pressure 2,301,225 will be released through the relief valves :2, as;

84 and GI, 92, l8 and through the safety valve After the auxiliary pistons 30 and ii and the main pressing plunger 32 have performed the full retraction stroke, the pumps 4 and 5 are shifted to neutral or substantially no-delivery position by means of the push rod 64 whereupon the press comes to a standstill. Since, due to the low pressure in the conduit. lllLthe tonnage control valve I09 has reached its previous position, all parts of the press are again in their initial piece, a reversible variable delivery pump, conduit means for conveying fluid from said pump I selectively to said motor or to said ram, means position and the press is ready for a new cycle.

While according to the embodiments shown in Figures 1 to 4, the press platen I has connected therewith a die comprising a plurality of punches, in this particular instance punches Ill and I42, whereas the press bed has associated therewith only one punch namely punch l8, it is understood of course that also the press bed may have connected therewith a plurality of punches.

If desired, the arrangement may also be the reverse of that shown in Figures 1 to 4, i. e., as illustrated in Figure 5, in which the plunger reciprocably mounted in the press bed cylinder It carries a platen I" having connected therewith punches I50 and iii whereas only one punch terrupting hydraulic communication between.

controlling the supply of pressure fluid from said reversible pump to said motor and said ram in a predetermined sequence for actuating the same, a one-way variable delivery pump operable independently of said reversible pump and continuously connected with said motor to supply fluid thereto in addition to the fluid supplied by said reversible pump, and to maintain a predetermined pressure on said platen for holding said platen stationary at the end of its pressing stroke, and means responsive to a predetermined fluid pressure on said platen for insaid motor and said reversible pump and estab- ,lishing hydraulic communication between said 152, is connected with the pressing platen I. The 7 operation of the embodiment of Figure 5 is exactly the same as that of the embodiments shown in Figures 1 to 4.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims and the invention. i

Having thus fully described my invention what I claim as new and desire'to se cure ,by Letters Patent, is:

1. In a multiple action press, supporting means for supporting a work piece to be shaped, a first press ram movable toward said work piece for exerting shaping pressure thereon, a second ram movable toward said first ram for exerting additional shaping pressure on said work piece,

clamping means operable to clamp said work piece against said support while said work piece is being shaped, a first pumping means for supplyin pressure fluid to said'rams, controlling for interrupting the supply of pressure fluid from said first pumping means to said first ram in response to a predetermined pressure acting upon said first ram to stop the advancement of said first ram towards said work piece, a second pumping means independent of said first pumpreversible pump and said r'am to cause movement of said ram toward said platen while the latter is held stationary.

3. In a multiple action press, supporting means for supporting a work piece to be shaped, clamping means for clamping said work piece against said support while it is being shaped, a press head comprising a main cylinder, a main ram having connected thereto a pressing platen and being reciprocably mounted in said main cylin der, a press bed comprising an auxiliary cylinder, an auxiliary fluid source for assisting said main auxiliary cylinder and adapted to cooperate with and to move toward said rriain ram for exerting shaping pressure on said work piece, a main fluid source, conduit means adapted to convey pressure fluid from said fluid source selectively to said main cylinder or to said auxiliary cylinder,

an auxiliary fluid source for assisting said main fluid source in its delivery to said main cylinder,

means for controlling the supply of pressure fluid ,means associated with said first pumping means from said main fluid source to said cylinders in a predetermined sequence to sequentially operate said main ram and said auxiliary ram, means for maintaining hydraulic connection between said main cylinder and said auxiliary fluid source while said main fluid source delivers fluid to said auxiliary ram, and means hydraulically connected with said fluid sources for causing simultaneous retraction of said rams.

4. In a multiple action press, a first hydraulically reciprocable plunger, first shaping means operable by said plunger to act upon one side of a work piece for shaping the same, means for clamping said work piece against a support while it is being shaped, a second hydraulically reciping means and comprising means for maintaining a predetermined pressure on said first ram during operation of said second ram to hold said first ram stationary, means for, establishiing hydraulic connection between said first E pumping means and said second ram when said first ram comes to a standstill to efl'ect movement of said second ram toward said first ram, and means responsive to a predetermined pressure on said second ram forcausing a retraction movement of said rams.

2. In a multiple action press, supporting means for supporting a work piece to be shaped, clamping'means for clamping said work piece against said support while it is being shaped,,a hydraulically operable ram movabletoward said. work piece for shaping the same, a fluidoperable motor having operativeiy connected thereto a press platen movable toward said ram for exrocable plunger, second shaping means operable by said second plunger to engage a work piece mined fluid pressure acting on said first plunger erting additional shaping pressure on said, work for moving said valve means into said second position, thereby interrupting the advancement of said first plunger and initiating operation of said second plunger, a second pressure fluid source independent of said first fluid source, and means for maintaining hydraulic connection between said second fluid source and said first plunger during the pressing strokes of both shaping means for supplementing said first fluid source during the pressing stroke or said first shaping means and for positively maintaining said first plunger stationary during the pressing stroke of said second shaping means.

5. In a multiple action press, a support for supporting a work piece to be shaped, means for clamping said work piece against said support while it is being shaped, a hydraulically operable plunger, a press platen movable by said plunger toward said workpiece to exert a first shaping pressure thereupon, a fluid operable ram movable toward said plunger for effecting a second shaping pressure on said work piece, first pumping means' for supplying pressure fluid to said plunger and said ram to operate the same, means for controlling the supply of pressure fluid to said plunger and said ram in a predetermined sequence, and second pumping means operable indepedently of said first pumping means for positively hold n said plunger in a stationary position while said ram is operative.

'6. In a, multiple action press, supporting means for supporting a work piece to be shaped, a fluid operable press plunger movable toward said work piece to exert shaping pressure thereupon, a hydraulically operable ram movable toward said press plunger for exerting additional shaping pressure on said work piece to perform an additional shaping operation, conduit means connected to a first fluid source for conveying pressure fluid from the latter to said press plunger and said ram, valve means associated with said conduit means and movable into a first position for connecting said first fluid source with said press plunger while preventing fluid connection between said first fluid source and said ram, and movable into a second position for connecting said first fluid source with said ram, a second sure on said press plunger during the pressing action or said ram.

7..In a multiple action press, supporting means for supporting a work piece, clamping means for clamping said work piece against said supporting means, two fluid operable plungers movable toward each other for exerting shaping pressure on said work piece, a first pressure fluid source operable selectively to deliver pressure fluid to one or the other of said plungers, a second fluid source operable to deliver pressure fluid only to one of said plungers, and controlling means movable selectively into a first position for directing the'delivery .of both fluid sources to one of said plungers, or into a second position for directing the delivery of said first fluid source to one of said plungers while said second fiuid source remains in hydraulic connection with the other plunger to maintain a predetermined pressure on the latter.

8. In a multiple action press, supporting means for supporting a work piece to be shaped, a first fluid operable press plunger operable to exert shaping pressure on said work piece, blank-holder means operable to clamp said work piece against said supporting means while it is being shaped, a second fluid operable press plunger movable toward said first plunger for exerting a shaping action on said work piece, a first pressure fluid source adapted selectively to supply pressure fluid to said first or to said second plunger, a second pressure fluid source independent of said first fluid source and continuously hydraulically connected with said first plunger, servomotor means associated with said second fluid source and responsive to a predetermined pressure acting on said first plunger for decreasing the delivery of said second fluid source, and controlling means movable into a first position for directing the delivery of said first fiuid source to said first plunger while preventing the delivery thereof to said second plunger, and movable into a second position for directing the delivery of said first fluid source to said second plunger while preventing the delivery thereof to said first plunger.

JOHAN A; MULLER, 

